Allowance for credit losses - Troubled debt restructurings loan count by type of modification (Details)	3 Months Ended
	Mar. 31, 2022 loans
Financing Receivable
Loan count	420
Reduction in interest rate
Financing Receivable
Loan count	43
Term Extension
Financing Receivable
Loan count	61
Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	288
Other
Financing Receivable
Loan count	28
Mortgages
Financing Receivable
Loan count	324
Mortgages | Reduction in interest rate
Financing Receivable
Loan count	1
Mortgages | Term Extension
Financing Receivable
Loan count	34
Mortgages | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	288
Mortgages | Other
Financing Receivable
Loan count	1
Commercial | CRE non-owner occupied
Financing Receivable
Loan count	1
Commercial | CRE non-owner occupied | Reduction in interest rate
Financing Receivable
Loan count	0
Commercial | CRE non-owner occupied | Term Extension
Financing Receivable
Loan count	0
Commercial | CRE non-owner occupied | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	0
Commercial | CRE non-owner occupied | Other
Financing Receivable
Loan count	1
Commercial | CRE owner occupied
Financing Receivable
Loan count	2
Commercial | CRE owner occupied | Reduction in interest rate
Financing Receivable
Loan count	1
Commercial | CRE owner occupied | Term Extension
Financing Receivable
Loan count	1
Commercial | CRE owner occupied | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	0
Commercial | CRE owner occupied | Other
Financing Receivable
Loan count	0
Commercial | Commercial and Industrial
Financing Receivable
Loan count	17
Commercial | Commercial and Industrial | Reduction in interest rate
Financing Receivable
Loan count	1
Commercial | Commercial and Industrial | Term Extension
Financing Receivable
Loan count	5
Commercial | Commercial and Industrial | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	0
Commercial | Commercial and Industrial | Other
Financing Receivable
Loan count	11
Consumer | Credit card
Financing Receivable
Loan count	30
Consumer | Credit card | Reduction in interest rate
Financing Receivable
Loan count	15
Consumer | Credit card | Term Extension
Financing Receivable
Loan count	0
Consumer | Credit card | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	0
Consumer | Credit card | Other
Financing Receivable
Loan count	15
Consumer | Personal loans
Financing Receivable
Loan count	45
Consumer | Personal loans | Reduction in interest rate
Financing Receivable
Loan count	25
Consumer | Personal loans | Term Extension
Financing Receivable
Loan count	20
Consumer | Personal loans | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	0
Consumer | Personal loans | Other
Financing Receivable
Loan count	0
Consumer | Auto Loan
Financing Receivable
Loan count	1
Consumer | Auto Loan | Reduction in interest rate
Financing Receivable
Loan count	0
Consumer | Auto Loan | Term Extension
Financing Receivable
Loan count	1
Consumer | Auto Loan | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	0
Consumer | Auto Loan | Other
Financing Receivable
Loan count	0
Consumer | Other
Financing Receivable
Loan count	0
Leasing
Financing Receivable
Loan count	0